Tape dubbing and divided master tape producing system

ABSTRACT

A high speed dubbing apparatus for producing magnetic tapes such as video, audio or computer soft tapes, is provided. Typical form of the apparatus may comprise 2 master tape playback devices for synchronously playing back 2 divided master tapes respectively recorded with 2 divided master signals obtained by dividing time-divisionally an original master signal having an original data sequence by 2 and for outputting the 2 divided master signals, a double speed recording signal producing device for time-compressing each of the 2 divided master signals to 1/2 to obtain a double speed recording signal from the 2 divided master signals while restoring the original data sequence in the double speed recording signal and a recording device for recording the double speed recording signal on a slave tape running at a speed which is twice the nominal playback speed of the slave tape.

This application is a continuation of U.S. application Ser. No.08/116,948, filed Sep. 3, 1993, now abandoned which is a continuation ofU.S. application Ser. No. 930,819, filed Aug. 14, 1992, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for dubbing a magnetictape such as video soft tape, audio soft tape or computer soft tape,etc., at high speed and a device for producing a divided master tape forhigh speed dubbing.

In this specification, terms involving a tape speed are defined inaccordance with the following definitions:

♭N Speed Playback"

To playback a tape at a running speed which is N times the speed withwhich the tape is recorded, where N is an integer larger than 1.

"N Speed Recording"

To record a signal reproduced from a master tape played back accordingto the "N speed Playback" on a recording medium, or to record a signalon a tape running at a speed which is N times a nominal playback speedof that tape, where N is an integer larger than 1.

"N Speed Dubbing"

A dubbing operation in which a master tape for dubbing is played backaccording to the "N speed Playback" and a resultant reproduced signalthus obtained is recorded as a recording signal on a slave tape runningat a speed which is N times a nominal playback speed of the slave tape,where N is an integer larger than 1.

In this case, although a transfer rate of the recording signal from amaster tape playback device to a slave tape recording device is N timesthat of the original recording signal which is used for recording themaster tape, actual running speeds of the master and slave tapes are notnecessarily identical each other but they can be different each other inthis "N Speed Dubbing" operation.

"Double Rate"

A status of signal transfer rate which is twice an original transferrate (signal transfer rate used for master tape recording).

"Real Time Speed"

This represents the "N Speed Playback", the "N Speed Recording", or the"N Speed Dubbing" where N is 1, or a tape speed which is equal to itsoriginal or nominal speed.

"Double Speed"

This represents the "N Speed Playback", the "N Speed Recording", or the"N Speed Dubbing" where N is 2.

DESCRIPTION OF THE RELATED ART

A dubbing apparatus in which a signal reproduced by a master tapeplayback device is supplied to a plurality of slave recording devices todub the signal on slave magnetic tapes in real time has been known.

Further, a contact print method in which a mirror image tape signalpattern is provided on a master tape having relatively large coerciveforce and is transferred to a slave magnetic tape by making a magneticsurface of the master tape in intimate contact with the slave magnetictape while externally applying a low frequency magnetic field theretohas been known as a high speed dubbing system.

Since the former conventional dubbing system is of a real time dubbingsystem in which the slave tapes are running at their nominal playbackspeed and recorded with a signal obtained by playing back the mastertape at its recording speed, efficiency of slave tape production is low.As to the contact print method, there are problems of degradation ofsignal frequency characteristics and/or S/N ratio.

The present invention is made in view of these problems and has anobject to provide a high efficiency, high performance dubbing apparatusand a divided master tape producing apparatus for realizing high speeddubbing.

Besides, in a digital VTR, etc., according to D2 standard (one of theindustry standards for digital video tape recording), an accompanyingaudio signal becomes discontinuous at a tape editing point. In order toprevent such signal discontinuity from being reproduced as noise, suchaudio signal is faded in at an editing start point and faded out at anediting end point, with a silence period of about 3 msec therebetween.

Therefore, when a divided master tape is produced or a produced dividedmaster tape is played back by using such VTR, an audio signal becomesdiscontinuous at an editing point provided during production of thedivided master tape.

The present invention is intended to solve such problems and has as anobject to provide a dubbing apparatus having no discontinuity of theaudio signal.

SUMMARY OF THE INVENTION

In order to solve the problems mentioned above, a dubbing apparatusaccording to the present invention is featured by comprising an N numberof divided master tape playback devices for synchronously playing back acorresponding number of divided master tapes. These divided master tapesrespectively recorded with N divided master signals obtained by dividingtime-divisionally an original master signal by N. The N divided mastersignals as outputted. The original master signal has an original datasequence, and an N speed recording signal producing device fortime-compressing each of the N divided master signals to I/N to obtainan N speed recording signal from the N divided master signals. Theoriginal data sequence is restored in the N speed recording signal. Therecording device is used for recording the N speed recording signal on aslave tape running at a speed which is N times a nominal playback speedof the slave tape.

According to another aspect of the present invention, a dubbingapparatus features each of the corresponding number of divided mastertapes is recorded with a first audio signal having a predetermined delaytime and a second audio signal having no. The dubbing apparatus furthercomprises a delay circuit for delaying the second audio signalreproduced from a corresponding one of the N number of divided mastertape playback devices, and an audio signal switching circuit forswitching between the first audio signal having a predetermined delaytime which is reproduced from a corresponding one of the N number ofdivided master tape playback devices. The second audio signal delayed bythe delay circuit. Making it possible to obtain an audio signal with nointerruptions.

Another and specific object of the present invention is to provide adivided master tape producing apparatus comprising a master tapeplayback device for playing back a master tape recorded with a mastersignal. A signal dividing device for dividing the master signalreproduced from the master tape playback device into an N number ofmaster signals at a predetermined time interval, and a divided mastertape recording device for producing divided master tapes by recordingthe divided N number of master signals on a corresponding number ofdivided master tapes, a corresponding one of the divided master signalsbeing arranged to be continuous on each of the divided master tapes, sothat N number of divided master tapes having a continuous signalrecorded thereon respectively, are produced.

The signal dividing device may further comprise a memory device forstoring the N number of master signals and a supplying device forsupplying the N number of master signals stored in the memory device tocorresponding recording units of the divided master tape recordingdevice. Accordingly, it is possible to prolong the time of intermittentrecording operation of the divided master tape recording device and torecord signals with improved stability.

According to another aspect of the present invention, a divided mastertape producing apparatus is featured by comprising a master tapeplayback device for playing back a master tape recorded with a mastersignal, a signal storing/dividing device for storing temporarily themaster signal reproduced from the master tape playback device anddividing the master signal stored therein into divided master signalsand for reading out the divided master signals, and a divided mastertape recording device for recording the divided master signals read outfrom the signal storing/dividing the continuously on magnetic tapes.Accordingly, it is possible to prolong the time of intermittentrecording operation of the divided master tape recording device and torecord signals with improved stability.

Other objects and further features of the present invention will beapparent from the following detailed description with respect topreferred embodiments of the invention when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a double speed dubbing apparatus accordingto an embodiment of the present invention;

FIG. 2(a) and FIG. 2(b) illustrate a recorded content of 2 dividedmaster tapes to be used in the apparatus in FIG. 1;

FIG. 3 is a block diagram of a double speed recording device for videotape according to an embodiment of the present invention;

FIG. 4(a), FIG. 4(b) and FIG. 4(c) shows an operation of a double speedrecording signal producing device according to an embodiment of thepresent invention;

FIG. 5 is a block diagram of a divided master tape producing apparatusaccording to another embodiment of the present invention;

FIG. 6 is a block diagram of a divided master tape producing apparatusaccording to a further embodiment of the present invention;

FIG. 7 is a block diagram of a divided master tape producing apparatusaccording to a still further embodiment of the present invention;

FIG. 8 is a block diagram of a recording device for producing a delayedaudio-signal-superposed divided master tape, according to an embodimentof the present invention;

FIG. 9 is a block diagram of a playback device for playing back adelayed audio-signal-superposed divided master tape, according toanother embodiment of the present invention; and

FIG. 10 is a series of time charts showing an operation of a playbackdevice for playing back a delayed audio-signal-superposed divided mastertape, according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described with referenceto the accompanying drawings.

FIG. 1 is a block diagram of a double speed dubbing apparatus accordingto the present invention.

The double speed dubbing apparatus "A" in FIG. 1 is adapted to dubmagnetic video tapes recorded with video and audio signals.

The dubbing apparatus "A" comprises first and second divided master tapeplayback devices 1 and 2, a double speed recording signal producingdevice 3, a signal distributor 4, a single or a plurality of doublespeed recording devices 5, a synchronous running control device 6, adouble rate reference signal generator 7 and a real time referencesignal generator 8.

FIG. 2(a) illustrates the recorded contents of divided master tapes MAand FIG. 2(b) illustrates the recorded contents of MB.

On a first divided master tape HA shown in FIG. 2(a), a video signal andan audio signal related to odd numbered color frames (CF) are recordedtogether with a time code and, on a second divided master tape FIB shownin FIG. 2(b), video and audio signals related to even numbered colorframes are recorded, similarly with a time code.

On each of the master tapes MA and MB, the time code is recorded as suchthat it increments 2 counts for every video color frame.

These divided master tapes MA and MB are played back by the first andsecond divided master tape playback devices 1 and 2 shown in FIG. 1,respectively.

The double rate reference signal generator 7 produces a video referencesignal or a timing signal 7a at double speed, that is, at a rate twicethe original recording rate.

The real time reference signal generator 8 produces a real-time timingsignal 8a on the basis of the double speed timing signal 7a.

The synchronous running control device 6 supplies the real-time timingsignal 8a through playback device control buses B1 and B2 to the firstand second divided master tape playback devices 1 and 2, respectively,and controls these devices 1 and 2 to run synchronized together at areal time playback speed, by monitoring time code signals 1a and 2a fromthe first and second divided master tape playback devices 1 and 2, andsending running control information through the control buses B1 and B2to the first and second divided master tape playback devices 1 and 2,respectively.

Further, the synchronous running control device 6 supplies the doublespeed timing signal 7a generated by the double rate reference signalgenerator 7 and running control information to the respective doublespeed recording devices 5 through the control bus B3 to control thedouble speed recording devices, so that they run at the double speed insynchronization with the playback operation of the respective mastertape playback devices 1 and 2.

The double speed recording signal producing device 3 for producing adouble speed recording signal comprises a bit rate converter 10 forvideo signal and a bit rate converter 20 for audio signal.

The video signal bit rate converter 10 responds to a real time videosignal 1b reproduced (with real time speed) by the first divided mastertape playback device 1 and to a real time video signal 2b reproduced bythe second divided master tape playback device 2, and makes the bitrates of these video signals 1b and 2b double, respectively, andcombines the respective video signals 1b and 2b into a single composedvideo signal 3a which is arranged in the color frame sequence.

Likewise, the audio signal bit rate converter 20 responds to audiosignals 1c and 2c outputted from the respective playback devices 1 and 2and doubles their bit rates respectively and combines them in thepredetermined sequence.

When video and audio signals recorded on the divided master tapes MA andMB are digital signals, the respective bit rate converters 10 and 20comprise temporary storage devices such as shift registers or RAMs,etc., and signal processing circuits such as read/write control devicestherefor, and write the digital signals to or read them from thetemporary storage devices in synchronism with the real time timingsignal 8a.

FIGS. 4(a) and 4(c) show respectively time code signals 1a and 2a, videosignals 1b and 2b (or audio signals 1c and 2c) which are reproduced fromthe first and second divided master tape playback devices 1 and 2 theninputted to the double speed recording signal producing device 3.

FIG. 4(b) shows the above video (or audio) signal being converted into adoubled bit rate, arranged in a order of color frames and outputted bythe double speed recording signal producing device 3 as a composed videosignal 3a (or audio signal 3b).

In a case where video and audio signals recorded on the divided mastertapes MA and MB are analog signals, the respective bit rate converters10 and 20 comprise, in addition to the components described above fordigital signals, A/D converters for converting reproduced analog signalsinto corresponding digital signals which are stored in the temporarystorage device and D/A converters for converting the digital signalshaving doubled bit rate read out from the temporary storage device intoanalog signals.

The signal distributor 4 comprises a plurality of buffer amplifiers,etc., which operate to supply double speed video signal 3a and doublespeed audio signal 3b outputted from the double speed recording signalproducing device 3 to video signal recording input terminals 5a andaudio signal recording input terminals 5b of the respective double speedrecording devices 5, respectively.

FIG. 3 is a block diagram of the double speed recording device 5 for avideo tape of VHS (one of the industry standard formats) system.

A magnetic tape 51 to be used as a divided master tape is transported bya capstan 53 which is driven by a capstan motor 52, and is recorded withvideo recording signal and audio recording signal at a double rate(doubled data transmission rate) and a control signal with respectivevideo and audio recording heads (not shown) and a control head 56 whilethe magnetic tape 51 is wrapped around and passed along a rotary drum 55driven by a drum motor 54 and is taken up on a take-up reel (not shown).

A video signal processing and recording circuit 57 derives a luminancesignal and a chrominance signal from the double rate video signal 3a,frequency-modulates the luminance signal, converts the chrominancesignal into lower frequency signal, combines them again and outputs aresultant mixture through a recording amplifier (not shown) to the videorecording head of the rotary drum 55 to record it on the magnetic tape51.

An audio signal recording circuit 58 frequency-modulates a left channelsignal of the double rate audio signal 3b to a frequency of 1.3 MHz×2and a right channel signal thereof to a frequency of 1.7 MHz×2, combinesthem and records a resultant signal on a video track portion of themagnetic tape 51 through the recording amplifier (not shown) and the FMaudio signal recording head (not shown) mounted on the rotary drum 55.

In this recording system, after an FM signal related to audio signal isrecorded on an under layer portion of the magnetic tape 51 in the formof under layer recording when the video signal is over-written on thesame track of a surface portion of the tape after the FM audio signal isrecorded.

For a longitudinal track audio signal, it is conventionally recorded ona longitudinal audio track through an audio recording amplifier (notshown) and an audio/control head 56.

The double speed timing signal (double rate video reference signal) 7agenerated by the double rate reference signal generator 7 is supplied toa synch. separator circuit 59. The circuit 59 separates, from the signal7a, a vertical synchronizing signal and outputs the latter to acapstan/drum control servo circuit 60 and a control pulse recordingcircuit 61.

The capstan/drum control servo circuit 60 controls the drum motor 54 andthe capstan motor 52 by using the vertical synchronizing signal as areference.

When a NTSC system video signal, is recorded at a double speed, therotary drum 55 having a pair of heads is control led such that itsrotational speed becomes 60 rps (revolution per second) when its realtime speed is 30 rps and simultaneously controls the capstan 53 as suchthat the running speed of the magnetic tape 51 becomes 6.67 cm/sec whenits real time speed is 3.335 cm/sec.

The control pulse recording circuit 61 produces a control pulse signalby wave-shaping the vertical synchronizing signal from the synch.separator circuit 59 and records it on a control track of the magnetictape 51 through the audio/control head 56.

With the construction mentioned above, since the double speed recordingsignal producing device 3 produces the double speed recording signals 3aand 3b shown in FIG. 4(b) on the basis of the reproduced signals 1b, 1c,2b and 2c which are obtained by playing the divided master tapes MA andMB in real time on the respective first and second divided master tapeplayback devices 1 and 2, it is possible to dub a slave tape at a doublespeed by recording the signals 3a and 3b in a double speed mode.

Although, in this embodiment, the original master tape is divided to twodivided master tapes, it is possible to perform a dubbing at a speed 3or more times the real time speed by increasing the dividing number ofthe tape up to 3 or more and converting its bit rate 3 or more times thereal time bit rate.

FIG. 5 is a block diagram of the divided master tape producing deviceaccording to the present invention.

The divided master tape producing apparatus "B" is adapted to producethe divided master tapes MA and MB which are respectively recorded with2 time-divisionally divided master signals of master video and audiosignals reproduced from an original master tape "M" (not shown),respectively.

In this embodiment, the divided master tapes MA and MB are produced onthe basis of the original master tape having a prerecorded time code.

The divided master tape producing device "B" comprises a master tapeplayback device 30, a signal divider 31, a first and second dividedmaster tape recording devices 32 and 33, a video reference signalgenerator 34 and a playback/recording control device 35.

The playback/recording control device 35 supplies a video referencesignal 34a outputted from the video reference signal generator 34 to themaster tape playback device 30 through a reproducing control bus B4 and,when the original master tape "M" loaded in the master tape playbackdevice 30 has a prerecorded time code, the control device 35 controlsthe playback device 30 to play the original master tape "M" at apredetermined speed by monitoring a reproduced time code signal 30a.

Further, the playback/recording control device 35 supplies the videoreference signal 34a through respective recording device control busesB5 and B6 to the respective divided master tape recording devices 32 and33 and controls the latter such that they record the video referencesignal 34a cyclically, thus time-divisionally, between the dividedmaster tape recording devices 32 and 33.

Alternatively, the control of the first and second divided master taperecording devices 32 and 33 may be performed by using the time codesignal 30a instead of the video reference signal 34a. Further, theplayback/recording control device 35 may control the first and seconddivided master tape recording devices 32 and 33 in synchronism with eachother by monitoring the time code from the master tape playback device30 and time codes 32c and 33c reproduced from the first and seconddivided master tape recording devices 32 and 33.

The signal divider 31 comprises a video signal divider 40 and an audiosignal divider 50.

The video signal divider 40 is adapted to output the reproduced videosignal 30b from the master tape playback device 30 by switchingalternately thus time-divisionally at a rate of color frame to supply avideo signal 40a of odd numbered color frames to a video signalrecording input terminal 32a of the first divided master tape recordingdevice 32 and a video signal 40b of even numbered color frames to avideo signal recording input terminal 33a of the second divided mastertape recording device 33.

The audio signal divider 50 serves to output the reproduced audio signal30c by switching it at the same timing as that of the video signaldivider 40 as such that audio signal 50a related to the odd numberedcolor frame to an audio recording signal input terminal 32b of the firstdivided master tape recording device 32 and an audio signal 50b relatedto the even numbered color frames to an audio recording signal inputterminal 33b of the second divided master tape recording device 33.

When the original master signal recorded on the original master tape "M"is an analog signal, the signal dividers 40 and 50 are constituted withvideo signal switching circuits (analog switches for video signal) etc.,respectively. When the signal recorded on the original master tape "M"is a digital signal, they may be constituted as such that signaldistribution is performed by logic circuits.

In the divided master tape producing device "B" constituted as mentionedabove, the respective divided master tape recording devices 32 and 33operate alternatively and intermittently in synchronism with theplayback of the original master tape "M" on the master tape playbackdevice 30 in the manner that the reproduced video signal 30b and thereproduced audio signal 30c from the original master tape "M" isdistributed cyclically and time divisionally at a predetermined intervalto respective divided master tape recording devices 32 and 33.Accordingly, the first and second divided master tapes MA and MB shownin FIG. 2(a) and FIG. 2(b) are produced.

Although, in this embodiment, the original master signal is divided totwo divided master tapes, it is possible to divide the original mastersignal by 3 or more.

FIG. 6 is a block diagram of another embodiment of the divided mastertape producing device according to the present invention.

The divided master tape producing device "C" comprises a memory device60 for temporarily storing video signals 40a and 40b and audio signals50a and 50b of respective time-division signals from a signal divider31C, a write/read control device 70 for control ling write and readoperations with respect to the memory device 60 and a playback/recordingcontrol device 80 associated with the write/read control device 70 forcontrolling operations of the master tape playback device 30 and therespective master tape recording devices 32 and 33.

The memory device 60 comprises a plurality of RAMs (random accessmemories) 60a, 60b, 60c and 60d. The respective RAMs 60a-60d are 2-portmemories each having a write port and a read port.

The write/read control device 70 responds to a video reference signalfrom a video reference signal generator 34 to control the write/readoperations.

The write/read control device 70 switches a write operation, through RAMcontrol buses B7 and B8, to either a first series RAMs 60a and 60b or asecond series RAMs 60c and 60d, according to a series select instruction80a given by the playback/recording control device 80.

The write/read control device 70 starts reading continuously, with aphase shifted from the write timing, the data stored up to the momentwhen a total data amount written in the respective RAMs 60a-60d reachesa preset amount, and concurrently sends a read start instruction 70a tothe playback/recording control device 80.

The playback/recording control device 80 responds to the read startinstruction 70a to send, through the recording device control buses B5and B6, an instruction for turning the first and second divided mastertape recording devices 32 and 33 into a recording mode.

It should be noted that the write/read control device 70 may beconstituted as such that it sends a pause instruction to theplayback/reproducing control device 80 to temporarily stop a reproducingoperation of the master tape playback device 30, when the respectiveRAMs 60a-60d are completed to be written with a predetermined amount ofdata, and during this stop period, the write/read control device 70reads the contents of the RAMs 60a-60d simultaneously and to turn thefirst and second divided master tape recording devices 32 and 33 into arecording mode through the playback/recording control device 80.

As mentioned above, since the divided master tape producing device "C"according to the present invention is constructed so that, after storingthe two divided master signals in the storage device 60, it suppliesthese signals to corresponding divided master tape recording devices 32and 33 continuously, it is possible to prolong the time for intermittentrecording operation of the first and second divided master taperecording devices 32 and 33, causing a recording to be more stable.

FIG. 7 shows a block diagram of a further embodiment of the dividedmaster tape producing apparatus according to the present invention.

The divided master tape producing apparatus "D" shown in FIG. 7comprises A/D converters 91 and 92 for converting an analog video signal90a and an analog audio signal 90b outputted from a master tape playbackdevice 90 into digital signals, respectively, memory circuits 93 and 94for storing an A/D converted video signal 91a and an audio signal 92band D/A converters 95 and 96 for converting the digital video and audiosignals 93a and 94a read out from the memory circuits 93 and 94 intoanalog signals, respectively.

When the master tape "M" and first and second divided master taperecording devices 97 and 98 are of digital type, respectively, the A/Dconverters 91 and 92 and the D/A converters 95 and 96 may be omitted.

A divided video signal 95a from the D/A converter 95 for video signal issupplied to video signal input terminals 97a and 98a of the first andsecond divided master tape recording devices 97 and 98 signal pathsthereto are regarded as first and second channels.

A divided audio signal 96a from the D/A converter 96 for audio signal issupplied to audio signal recording input terminals 97b and 98b of therespective divided master tape recording devices 97 and 98.

The respective memory circuits 93 and 94 are constituted with 2-portRAMs each having a write port and a read port.

The digital signals 91a and 92a from the A/D converters 91 and 92 arewritten in the memory circuits 93 and 94 according to a write addressand write timing signals supplied from a write control device 100through a write control bus 99 and the stored signals are read outtherefrom according to a read address and read timing signals, etc.,supplied from a read control device 102 through a read control bus 101.

The memory circuits 93 and 94 and the write and read control devices 100and 102 constitute a signal storing/dividing device 103 which producestwo divided master signals divided at a predetermined time interval bytemporarily storing the divided signals and changing reading order ofthe divided signals thereafter.

A reference clock generator 104 produces a timing signal 104a whichprovides references for sampling period of the A/D converter and a writetiming.

A playback/recording control device 105 controls a reproducing operationof the master tape playback device 90 and recording operations of thefirst and second divided master tape recording devices 97 and 98.

The playback/recording control device 105 controls start, stop andreproducing speed of the master tape playback device 90 through aplayback control bus 105a and controls start, stop, recording speed andrecording position of the tapes of the first and second divided mastertape recording devices 97 and 98 through similar recording control buses105b and 105c.

The playback/recording control device 105 turns the master tapereproducing device 90 into a playback state and simultaneously suppliesa writing start instruction 105d to the control device 100 for causingthe memory circuits 93 and 94 to start writing.

The read control device 102 sends a recording instruction 102a to theplayback/recording device 105 at a time when a series of writeoperations completes or digital signal data has been written insubstantially a half of a whole memory area by the series of writeoperations. The recording instruction signal 102a contains aninformation indicative of whether a signal to be read belongs to thefirst channel or the second channel mentioned before and theplayback/recording control device 105 turns the assigned first or seconddivided master tape recording device 97 or 98 into recording state.

The read control device 102, when the recording instruction 102a isoutputted, reads the respective memory circuits 93 and 94. This readingis performed as such that a signal which is continuous in time isdivided into two series signals at a predetermined time interval. Forexample, after the recording instruction 102a is sent to the firstdivided master tape recording device 97, data corresponding to a periodof 0-10 seconds of the master tape playback time is read out and thendata of 20-30 seconds is read out, and, so on. Then, after the device 98is selected in response to the recording instruction 102a forwarded tothe device 98, data of 10-20 and 30-40 seconds and so on are read out.

In the divided master tape producing apparatus "D" according to thepresent invention, the time divisional signal division is performed bychanging the sequence of reading signals stored in the memory circuits93 and 94 then the read out signals are recorded in the correspondingfirst and second divided master tape recording devices 97 and 98,accordingly, the divided master tapes are produced efficiently.Although, in this embodiment, the signal is divided by changingaddresses at the reading of the memory circuits 93 and 94, it ispossible to constitute a system as such that signals in the respectivechannels are read out continuously by changing addresses at the time ofwriting.

Although it is possible to temporarily suspend the playback of theoriginal master tape at a time when the writing to the whole areas ofthe memory circuits 93 and 94 completes, a new signal may be written inan address the content of which has been read out without suspending thereproduction of the original master tape, by suitably setting a timedifference between the write and the read according to capacities of thememory circuits 93 and 94.

For the intermittent driving of the first and second divided master taperecording devices 97 and 98, the playback/recording control device 105may be constructed as such that the recording position is exactlycontrolled by rewinding a predetermined amount of the tape right afterthe recording is stopped, starting the tape running at a time when therecording instruction 102a is supplied from the read control device 102,returning a read enable signal at a predetermined timing by monitoring atape running control signal prerecorded on the divided master tape, andstart reading of the memory circuits 93 and 94 in response to the readenable signal.

FIG. 8 is a block circuit diagram of a recording device for producing adelayed audio signal superposed divided master tape according to thepresent invention.

A delayed audio signal superposed divided master tape recording device110 is a modified version of the first and second divided master taperecording devices 32, 33, 97 or 98 shown in FIGS. 5-7 with portionsthereof modified. The delayed audio signal superposed/divided mastertape recording device 110 comprises a recording device 111 having 2separate audio signal recording input terminals AI1 and AI2 and a delaycircuit 112.

A video signal "V" is supplied to a video signal recording inputterminal VI of the recording device 111, an audio signal "AU" issupplied to the recording device 111 to its audio input terminal AI1directly and to its audio input terminal AI2 through the delay circuit112, respectively.

Accordingly, two kinds of audio signals are recorded on a divided mastertape by using this divided master tape recording device 110, one beingwith a delay and the other without the delay.

FIG. 9 is a block diagram of a delayed audio signal superposed anddivided master tape reproducing apparatus according to the presentinvention.

The delayed audio signal superposed and divided master tape reproducingapparatus 120 shown in FIG. 9 has a similar construction to that shownin FIG. 1, with some modifications of the first and second dividedmaster tape reproducing devices 1 and 2.

The delayed audio signal superposed and divided master tape reproducingapparatus 120 comprises a reproducing, device 121 having two channelsignal reproducing output terminals A01 and A02, a delay circuit 122 fordelaying an audio signal reproduced without delay and supplied from theoutput terminal A01, a switching circuit 123 for switching between anaudio signal 122a delayed by the delay circuit 122 and an audio signalrecorded with delay and supplied from the output terminal A02 and aswitching control circuit 124 for controlling a switching operation ofthe switching circuit 123.

A delay time of this delay circuit 122 is same as that of the delaycircuit 112 provided within the delayed audio signal superposed anddivided master tape reproducing apparatus 110.

A reproduced video signal VS from the video signal output terminal VO issupplied directly to the double speed recording signal producing device3 shown in FIG. 1 and the reproduced audio signal AS from the switchingcircuit 123 is supplied to the device 3.

The switching control circuit 124 controls the switching between twokinds of audio signal by supplying a switching control signal 124a tothe switching circuit 123 at a preset timing so as not cause a loss ofaudio signal in the fade-in and fade-out switching process discussedlater.

The switching timing is selected such that it is synchronous with anediting interval during production of the divided master tapes.

In a case where the divided master tapes carry control signals relatedto tape running positions, the apparatus may be constituted as such thatit determines editing positions according to the control signal, toproduce the switching control signal 124a.

FIG. 10(a)-(h) shows a series of time chart of an operation of the audiosignal switching circuit.

FIG. 10(a) illustrates a signal processing operation of fade-in andfade-out at the editing points.

FIG. 10(b) shows an audio signal to be recorded on the audio signalsuperposed and divided master tape, where the audio signal is notdelayed, and FIG. 10(c) shows another audio signal to be recorded on theaudio signal superposed and divided master tape, where above anotheraudio signal is delayed by the delay circuit 112, and Td is a delay timeof the delay circuit.

FIGS. 10(d) and 10(e) show reproduced audio signals obtained at theoutput terminals A01 and A02 of the reproducing apparatus 121 and FIG.10(f) shows the signal 122a delayed by the delay circuit 122.

FIG. 10(g) illustrates the switching control signal 124a for selectingeither one of the signals shown in FIGS. 10(e) and 10(f) as the audiosignal output AS and FIG. 10(h) shows the audio signal output AScomposed by the switching.

It is possible to obtain a continuous audio signal having no loss bydelaying, when reproduced, the audio signal which was recorded withoutdelay to coincide it with the audio signal recorded with delay as shownin FIGS. 10 (e) and 10(f), and switching between them by the switchingcircuit 123 as such that the fade-in and fade-out portions thereof areexcluded.

Similarly, it is possible to reproduce an audio multiplexed stereosignal etc., when the divided master recording device and thereproducing device respectively have 4 channels or more.

Although the embodiments have been described for dubbing at a doublespeed, the dubbing speed can be three or more times by increasing thenumber of the divided master tape recording devices and the dividedmaster tape reproducing devices and changing the dividing number of amaster signal.

Further, in the described embodiments, the signal is divided andcombined every color frame, but it is possible to convert the bit rateevery segment, every field, every frame or every two frames.

Since the dubbing apparatus according to the present invention isequipped with the N (times) speed recording signal producing device inwhich reproduced signals in N channels are time compressed to 1/N,respectively, and sequences of the respective signals are restored to besame as that of the original master signal, it is possible to perform adubbing at the N times speed by using N times speed recording devices.

Further, since the divided master tape producing apparatus according tothe present invention divides a reproduced signal from an originalmaster tape at a predetermined time interval and supplies them to therespective master tape recording devices, it is possible to produce aplurality of divided master tapes by a single reproducing operation.

Further, since the divided master tape producing apparatus storessignals divided into N channels in memory devices and then continuouslyreads them out and supplies them to corresponding divided master taperecording devices, it is possible to prolong the time of intermittentrecording operation of the divided master tape recording device andrecord signals with improved stability.

Further, since the divided master tape producing apparatus according tothe present invention stores the reproduced original master signal ofthe master tape temporarily in a memory circuit and then reads andrecords it by corresponding divided master tape recording devices, it ispossible to produce the divided master tapes efficiently.

Further, since the dubbing apparatus according to the present inventiondelays the signal, which is originally recorded on a tape without delay,by a delay circuit to remove a time difference from the signal recordedwith delay and selects portions of audio signal which are not subjectedto fade-in and fade-out process, it is possible to obtain a continuousaudio signal even when a device which performs fade-in and fade-outprocessings of audio signal at editing points, is used.

What is claimed is:
 1. A divided master tape producing apparatuscomprising:an original master tape playback device for playing back anoriginal master tape recorded with an original master signal having anoriginal signal sequence; signal dividing means for dividing saidoriginal master signal time-divisionally into predetermined signalsegments of equal length, each of said predetermined signal segmentshaving a preselected time code and being one of a group consisting ofone video field, one video frame, one color frame and two video framesforming an N number of divided master signals by assigning saidpredetermined signal segments sequentially and cyclically between said Nnumber of divided master signals based on said time code where N isgreater than 1, said signal dividing means comprising means for storingcontents of said original master signal reproduced from said originalmaster tape playback device and controlling means for controlling saidstoring means so as to produce said N number of divided master signalsbeing outputted from said storing means; and N number of master signalrecording devices for recording said N number of divided master signalsrespectively on N number of master tapes, said controlling means causingsaid N number of master signal recording devices to drive intermittentlysaid N number of master tapes to be recorded, so that each of said Nnumber of divided master signals becomes continuous without timeinterruption on said N number of tapes.
 2. A dubbing apparatuscomprising:an original master tape playback device for playing back anoriginal master tape recorded with an original master signal having anoriginal signal sequence; signal dividing means for dividing saidoriginal master signal time-divisionally into predetermined signalsegments of equal length, said signal segments of equal length eachhaving a preselected time code thereby forming an N number of dividedmaster signals by assigning said predetermined signal segmentssequentially and cyclically between said N number of divided mastersignals based on said time code where N is an integer greater than 1; Nnumber of master signal recording devices for recording said N number ofdivided master signals respectively on N number of master tapes, controlmeans for causing said N number of master signal recording devices todrive intermittently said N number of master tapes to be recorded, sothat each of said N number of divided master signals becomes continuouswithout time interruption on said N number of master tapes; N number ofmaster tape playback devices for synchronously and simultaneouslyplaying back at a real time speed said N number of master tapesrespectively; N-times speed recording signal producing means fortime-compressing each of said N number of divided master signalsreproduced from said N number of master tape playback devices into 1/Nto obtain N-times speed recording signals while restoring said originalsignal sequence in each of said N-times speed recording signals; andrecording means for recording said N-times speed recording signals on aplurality of slave tapes each running at a speed which is N-times anormal playback speed of said slave tapes.
 3. A dubbing apparatusclaimed in claim 2, wherein said signal dividing means comprises memorymeans for storing said N number of divided master signals and means forsupplying said N number of divided master signals stored in said memorymeans to said N number of master signal recording devices.
 4. A dubbingapparatus claimed in claim 2, wherein said signal dividing meanscomprises means for storing contents of said original master signalreproduced from said original master tape playback device and means forcontrolling said storing means so as to produce said N number of dividedmaster signals being outputted from said storing means and to supplysaid N number of divided master signals to said N number of mastersignal recording devices.
 5. A dubbing apparatus as claimed in claim 2,wherein said original master signal includes an original audio signaland each of said N number of master tapes is recorded with a first audiosignal having a predetermined delay time, and a second audio signalhaving no delay, said first and second audio signals are derived fromsaid original audio signal, and each of said first and second audiosignal has fade-in and fade-out editing points, said dubbing apparatusfurther comprises a delay circuit for delaying said second audio signalreproduced from a corresponding one of said N number of master tapeplayback devices, and audio signal switching means for selectivelyoutputting one of said first audio signal and said second audio signaldelayed by said delay circuit, so that said one of the first and secondaudio signals selected by said audio signal switching means foroutputting, does not contain said fade-in and fade-out editing points.6. A dubbing apparatus claimed in claim 2, wherein said original mastersignal is in an analog signal and said signal dividing means comprisesan analog to digital conversion means for converting said originalmaster signal into a digital format to produce said N number of dividedmaster signals.
 7. A dubbing apparatus claimed in claim 2, wherein saidN number of master signal recording devices are digital devices.
 8. Adubbing apparatus claimed in claim 2, wherein said N number of dividedmaster signals respectively recorded on N number of master tapes are ina digital format, said N-times speed recording signal producing meanscomprises bit rate converters with memory means and said N number ofdivided master signals in the digital format are written in and read outfrom said memory means for producing said N-times speed recordingsignals.
 9. A dubbing apparatus claimed in claim 2, wherein said Nnumber of master tape playback devices play back said N number of mastertapes synchronously and simultaneously and are controlled by a timingsignal supplied thereto.
 10. A dubbing apparatus as claimed in claim 2,wherein said equal length is a length of one of a group consisting ofone video field, one video frame, one color frame and two video framesof said original master signal.
 11. A dubbing apparatus claimed in claim2, wherein N is 2 and said original master signal is time-divisionallydivided into odd numbered color frames and even numbered color frames.